Polycarbonate resins are widely used in the various fields such as the electric or electronic apparatus fields for office automation apparatuses, information and communication apparatuses and household electric apparatuses and the like, the automobile field, the lighting apparatus field and the building field due to the excellent impact resistance, heat resistance and dimensional stability. Although the polycarbonate resin has the self-extinguishing property by itself, it is desired that the flame-retarding property is enhanced to further improve the safety when the resin is used as a raw material for electric and electronic apparatuses such as office automation apparatuses, members of automobiles and members of lighting apparatuses.
As the method for improving the flame-retarding property of the polycarbonate resin, halogen-based flame retardants such as halogenated bisphenol A and halogenated polycarbonate oligomers have been used in combination with an auxiliary flame retardant such as antimony oxide due to the excellent efficiency of flame retardation. However, in recent years, a method for flame retardation using a flame retardant containing no halogens is required from the standpoint of the safety and the great effect of the flame retardants containing a halogen on the environment during incineration. Since the excellent flame-retarding property and the effect as a plasticizer are exhibited simultaneously when an organic phosphorus-based flame retardant, in particular, an organic phosphoric acid ester compound, is used as the flame retardant containing no halogens, flame-retardant polycarbonate resin compositions using the organic phosphoric acid ester compound are proposed.
However, it is necessary that the organic phosphoric acid ester compound be used in a relatively great amount for flame retardation of a polycarbonate resin with the organic phosphoric acid ester compound. To produce a thinner molded article having a great size, it is necessary that the molding temperature be elevated since the polycarbonate resin requires a high temperature for molding and has a great melt viscosity. Therefore, the organic phosphoric acid ester compound is not always satisfactory from the standpoint of the environment of molding and the appearance of the product due to drawbacks such as attachment of the compound to a mold and generation of gases during the working although the compound contributes to exhibiting the flame-retarding property. The molded product obtained from the flame-retardant polycarbonate resin composition using the organic phosphoric acid ester compound has a drawback in that a decrease in impact strength and discoloration take place after exposure to a high temperature or to a high temperature and a high humidity.
In Japanese Patent Application Laid-Open No. Showa 50(1975)-98546, to overcome the above problems, it is proposed that a polycarbonate resin is made flame retardant by using a small amount of a metal salt of a polymeric aromatic sulfonic acid such as the sodium salt of a polystyrenesulfonic acid. However, when polystyrene is sulfonated in accordance with a conventional process and neutralized with sodium hydroxide and a polycarbonate is made flame retardant with the obtained sodium polystyrenesulfonate, a drawback arises in that the appearance of the product becomes poor due to poor dispersion of sodium polystyrenesulfonate although the excellent flame-retarding property can be obtained.
For a flame-retardant polycarbonate resin composition, it is also required that a material for molding which is made flame retardant while the excellent physical properties proper to the polycarbonate resin is retained be developed. To satisfy the requirement, for example, a flame-retardant polycarbonate resin composition obtained by adding an organic alkali metal salt or an organic alkaline earth metal salt and an organopolysiloxane to a polycarbonate resin is proposed in Japanese Patent Application Laid-Open No. Heisei 8(1996)-176425. However, this composition has a drawback in that dusts are easily attached to the surface of the product obtained by molding the flame-retardant polycarbonate resin composition.
As described above, the development of a flame-retardant polycarbonate resin composition which provides an article exhibiting excellent flame-retarding property and retention of the antistatic property to prevent the attachment of dusts, has been desired.
The present invention has an object of providing a flame-retardant polycarbonate resin composition which provides an article exhibiting excellent flame-retarding property and retention of the antistatic property to prevent the attachment of dusts and a molded article thereof.